The span length efficiency of tubercles on swept wings

Resumo

© 2018, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.The study of wavy leading edge phenomena on finite wings conducted on recent research has shown results that demonstrate improvements in aerodynamic characteristics for certain configurations. The most important outcomes were observed on swept and swept-tapered wings, attaining improvement in lift coefficients of around 20% when compared with their equivalent baseline models. This increase on lift force is associated to the fact that the wavy configurations exhibit a delay on the stall angle due to the effect of the tubercles, which main effect is to delay the stall progression from tip to root by keeping the flow attached on the leading edge at high angles of attack. Visualization results confirmed larger effect of these phenomena on the wingtip area. In order to give continuity to previous works that investigated swept wing with wavy leading edge, obtain a deeper knowledge of this phenomena and delimit the design space in which the wavy leading edge could be efficiently applied, a series of experiments were conducted on sixteen wing configurations including swept angles of 30 and 50 degrees, taper ratio of 1 and 0.5, and wavy span length of 20, 40 and 100% (from tip to root). All models had an underlying NACA 0020 airfoil and a wavy geometry with amplitude A = 0.03 and wavelength λ = 0.11 considering the root chord as reference. The purpose of this research consist in evaluating of drag and lift forces at Reynolds number of Re = 200, 000 for all models showing comparative results with the baseline wings. In addition, a flow visualization analysis using oil technique was included in order to better understand the involved phenomena.